The present invention relates to safety guard devices for rotating cutters, and more particularly the present invention relates to improved safety guard assemblies for the cutter blade of rotary-type mowing machines such as lawn mowers and the like. Rotary cutter lawn mowers utilize a rectangular substantially flat cutter blade mounted within a shroud or housing closed at its top and periphery, and open at its bottom. The shroud or housing is often provided with a discharge aperture or chute for laterally discharging the cut grass. The rotating blade is mounted at its center on the end of a vertically disposed shaft, directly driven by a prime mover such as a small internal combustion engine, electric motor or the like, or driven from the prime mover by any appropriate means such as a pulley and V-belt drive or the like. The rotating blade has a portion of its leading edge on each end ground to a sharp cutting edge, such as to continuously cut the grass to a certain height along the path of travel of the mower.
Such rotary mower devices are prone to be damaged as a result of the cutter blade impacting upon objects hidden in the grass of disposed in the path of the mower, such as stones, tree branches and the like. Upon impact with such an object, the cutting edge of the cutter blade is damaged, and loose pebbles, stones or other hard objects are projected as a result of impacting with and being propelled by the rapidly rotating blade with a relatively high velocity which may cause injuries to the operator of the mower and persons standing by, or which may cause property damages. It is not uncommon for the hand or a finger, or the foot, of a person or child, or for a domestic animal to be caught in the path of the rotating cutter blade, with considerable injuries thus resulting.
There is consequently a need for a safety guard device for rotary type cutter blades such as are used in rotary grass mowers, and the like, to prevent accidental contact of the cutting edge of the rapidly rotating cutter blade with an object other than the grass to be cut and, alternatively or in addition, for permitting the blade to ride over an immovable obstacle without seriously deteriorating the blade cutting edge or the blade itself.